1. Field of the Invention
This invention relates to a speaker, especially a speaker having a diaphragm having a ring-shape inner diaphragm, a voice coil being mounted on an outer edge thereof, and a ring-shape outer diaphragm, the voice coil being mounted on an inner edge thereof.
2. Description of the Related Art
A speaker generally includes a diaphragm for generating sound wave, a voice coil bobbin formed integrally with the diaphragm and elastically supported by a damper to be vibrated, and a voice coil wound around the voice coil bobbin and disposed in a magnetic gap.
The diaphragm is vibrated through the voice coil bobbin by flowing electric current according to playback sound in the voice coil, so that this speaker generates sound wave as acoustic energy.
Objects to be Solved
Recently, DVD player becomes popular so that a speaker is required to have capability for playback in wide frequency range. Therefore, it is expected to eliminate a sound noise as much as possible by means of reducing a peak value of amplitude at resonance frequency in frequency characteristics of a speaker.
This invention has been accomplished to realize the above expectation and an object of this invention is to provide a speaker capable to playback in wide frequency range by means of reducing a peak value of amplitude of resonance frequency in frequency characteristics of a speaker.
How to Attain the Object
In order to attain the objects, a speaker according to this invention, includes a diaphragm having a ring-shape inner diaphragm, a voice coil mounted on an outer edge of the inner diaphragm, and a ring-shape outer diaphragm, the voice coil mounted on an inner edge of the outer diaphragm, wherein resonance frequencies of the inner diaphragm and the outer diaphragm are differed from each other.
In the above-mentioned speaker, resonance frequencies of the inner diaphragm and the outer diaphragm are different. Therefore, in frequency characteristics of the whole diaphragm synthesized with frequency characteristics of the inner diaphragm and frequency characteristics of outer diaphragm, a peak value of amplitude at resonance frequency can be reduced and the curve of frequency characteristics becomes flatter.
Furthermore, in the speaker according to the invention as referred to above, the inner diaphragm and the outer diaphragm are respectively formed with curvature along their radial directions thereof, and radii of curvatures of the surfaces having the curvatures of the inner and outer diaphragms are differed from each other.
In the above-mentioned speaker, to differ radii of curvatures of the inner and outer diaphragms, resonance frequencies of the inner diaphragm and the outer diaphragm can be easily differed from each other. In addition, deformation and/or split vibration of the diaphragm at high frequency can be prevented by means of curving the surface.
Furthermore, in the speaker according to the invention as referred to above, an angle formed between a straight line perpendicular to a direction of winding wire of the voice coil and a tangential line to the curved surface of the inner diaphragm at the outer edge of the inner diaphragm and an angle formed between a straight line perpendicular to a direction of winding wire of the voice coil and a tangential line to the curved surface of the outer diaphragm at the inner edge of the outer diaphragm are differed from each other.
In the above-mentioned speaker, to differ the angle formed between the straight line perpendicular to the direction of winding wire of the voice coil and the tangential line to the curved surface of the inner diaphragm at the outer edge of the inner diaphragm and the angle formed between the straight line perpendicular to the direction of winding wire of the voice coil and the tangential line to the curved surface of the outer diaphragm at the inner edge of the outer diaphragm, resonance frequencies of the inner diaphragm and the outer diaphragm can be easily differed from each other. In addition, deformation and/or split vibration of the diaphragm at high frequency can be prevented by means of curving the surface.
Furthermore, in the speaker according to the invention as referred to above, the inner diaphragm and the outer diaphragm are respectively formed with curvature along their radial direction thereof, and radii of curvatures of the surfaces having the curvatures of the inner and outer diaphragms are differed from each other, and the angle formed between the straight line perpendicular to a direction of winding wire of the voice coil and the tangential line to the curved surface of the inner diaphragm at the outer edge of the inner diaphragm and the angle formed between the straight line perpendicular to a direction of winding wire of the voice coil and the tangential line to the curved surface of the outer diaphragm at the inner edge of the outer diaphragm are differed from each other.
In the above-mentioned speaker, to differ radii of curvatures of the inner and outer diaphragms, and to differ the angle formed between the straight line perpendicular to the direction of winding wire of the voice coil and the tangential line to the curved surface of the inner diaphragm at the outer edge of the inner diaphragm and the angle formed between the straight line perpendicular to the direction of winding wire of the voice coil and the tangential line to the curved surface of the outer diaphragm at the inner edge of the outer diaphragm, resonance frequencies of the inner diaphragm and the outer diaphragm can be easily differed from each other. In addition, deformation and/or split vibration of the diaphragm at high frequency can be prevented by means of curving the surface.
Furthermore, in the speaker according to the invention as referred to above, areas of the inner diaphragm and the outer diaphragm are equalized with each other.
In the above-mentioned speaker, to equalize areas of the inner diaphragm and the outer diaphragm, sound pressure levels of the inner diaphragm and the outer diaphragm are equalized with each other, in other words, peak values of amplitudes at respective resonance frequencies of the inner diaphragm and the outer diaphragm can be equalized with each other. Therefore, the peak value of amplitude at the resonance frequency of the whole diaphragm can be reduced more and the curve of frequency characteristics becomes flatter.
Furthermore, in the speaker according to the invention as referred to above, the speaker is a horn type.
In the above-mentioned speaker, an efficiency of generating a sound wave can be increased by using a horn type speaker.
Furthermore, in the speaker according to the invention as referred to above, the inner diaphragm and the outer diaphragm are formed integrally.
In the above-mentioned speaker, forming the inner diaphragm and the outer diaphragm integrally, the inner diaphragm and the outer diaphragm can be manufactured easily and the voice coil can be also easily mounted on the diaphragm.
Furthermore, in the speaker according to the invention as referred to above, the resonance frequencies are in high-frequency range.
In the above-mentioned speaker, the peak values of amplitudes at high frequency are reduced so that the curve of frequency characteristics becomes flatter.
The above and other objects and features of this invention will become more apparent from the following description taken in conjunction with the accompanying drawings.